Light provides enormous potential for data transmission with very high data rates. In some cases, optical data transmission uses optical fibers as the transmission medium because light can be guided in fibers over very long distances with very low losses, while avoiding alignment issues and atmospheric influences. However, there also are applications for free-space optical (FSO) communications that use light propagating in free space to transmit data wirelessly. Free-space point-to-point optical links can be implemented, for example, using infrared (IR) or near-IR light (e.g., 750-1600 nm). These systems typically use laser transmitters and offer a cost-effective protocol-transparent link with high data rates (e.g., 10 Gbit/s per wavelength).
Optical data transmission is increasingly used in various fields (e.g., telephony, Internet traffic, cable television) primarily for larger transmission distances of at least a few kilometers. There is, however, a growing trend to consider using optical systems for smaller and smaller transmission distances. For example, there is the potential to use optical data transmission for communications between mobile devices such as smartphones, which have become popular and which consumers have come to rely on for many aspects of their daily life.